The aim of the proposed research is to explore the innovative idea that the keratocytes of the normal human cornea may function as two separate sub-populations and/or that antigenically different keratocytes exist. This postulate stems from our recent preliminary observation that the keratocytes of the posterior one-third of the human corneal stroma stained immunohistochemically with polyclonal antibodies against neuronal-specific enolase (NSE) whereas those of the anterior two-thirds did not. It is proposed to develop a technique that will allow the keratocytes of the anterior stroma to be harvested in vitro separately from the cells of the posterior stroma. The NSE expressivity of these cultured cells will be determined using affinity-purified immunohistochemical markers. The investigation is expected to elucidate whether the posterior keratocytes are induced to express NSE due to the influence of the subjacent corneal endothelium, or if this character is lost or masked in the anterior keratocytes, perhaps due to an interaction with the epithelium. Because the presence of NSE in normal cells is believed to indicate neural differentiation, this study will also address the question of the neural crest or other embryonic origin of the stromal cells of the cornea in man. The results obtained will form the basis for further multidisciplinary studies that can probe in greater detail the biologic role of the factors endogenous to the human cornea in health and disease, as well as the interactions between corneal cell types. It is envisaged that this preliminary study could provide insight into certain dystrophic and degenerative disorders in man that are confined essentially to the anterior or to the posterior corneal stroma.